In high performance magnetic disk memories of the "Winchester" type, the read/write heads are maintained out of contact with their respective disk surfaces, the air flow induced by the rapidly rotating disks being sufficient to support the heads which, in effect, are flown at a small distance from the disk surfaces. To prevent damage to the data storage portions of the disk surfaces as a result of head contact, a part of each disk is dedicated as a parking or landing zone within which the heads may be safely brought into contact with the disk surfaces. The parking zone, or track, is typically located radially inward of the data tracks and it is common practice to latch the head/arm assembly in the parking position to protect the disk surfaces and the integrity of the recorded data during handling and shipping of the disk memory.
Various head latching techniques are in use. In accordance with one type, the heads are held in the parking zone by a permanent magnet. Because of the range of the magnetic field, however, the heads, when operating in the read/write mode, cannot be brought too close to the parking zone where their motion can be influenced by the latch magnet field. This constraint places a limit on the number of data tracks.
Another head latching arrangement utilizes a solenoid-operated mechanism in which the solenoid is energized to unlatch the heads. Although failsafe, this approach requires additional power constantly applied to the solenoid during the normal operation of the disk memory.